TOPICS > Science

Arctic Ice Pack Reveals Warming Trend

November 8, 2004 at 12:00 AM EDT


TOM BEARDEN: This is the Coast Guard cutter Healy, nudging her way through ice flows in the Arctic Ocean, north of Barrow, Alaska. The Healy is an ocean-going, icebreaking laboratory doing climate change research in one of the Earth’s coldest and loneliest places. Although the ice pack is far less dense in the summer, it’s still formidable. Daniel Oliver is the ship’s captain.

CAPT. DANIEL OLIVER: We’ve got a kind of an undercut forefront on the bow, and that allows the front of the ship more easily to ride up on the ice and as the weight of the ship starts to bear down on the ice it breaks it free and we continue to move ahead.

TOM BEARDEN: The mission of the 43 scientists aboard is to study global climate change. There is no question that the Arctic has been getting warmer. In fact, in a report released today by the Arctic Council — an intergovernmental forum made up of eight Arctic nations — and the International Arctic Science Committee, scientists independent of the Healy’s researchers, found that winter temperatures in Alaska and Western Canada have increased on average by 5 to 7 degrees over the past 50 years. And in the next century, ocean temperatures are expected to rise by 13 degrees globally. Sea levels have risen by an average of 3 inches over the past 20 years, and are expected to increase by 4 inches to 3 feet in the next 100 years.

But scientists don’t agree on how much of these changes might be due to human activity and how much might be natural variability. Back on the Healy, satellite data reveals the total amount of the Arctic ice pack has decreased over the past 20 years. And during that period of time, the rate of warming was eight times as much as it had been over the last 100 years.

What the researchers learn here may have implications far beyond the region. Lee Cooper is chief scientist for the project called the Western Arctic Shelf Basin Interaction Project, or SBI. It’s a joint effort by the National Science Foundation, which also funds the NewsHour’s Science Unit, and the Office of Naval Research.

LEE COOPER, University of Tennessee: There are climate changes that are potentially important for the rest of the United States, as well as there are great costs that may occur if we allow climate change to continue unimpeded. There are going to be great costs and society is going to have to bear in terms of sea level rise, in terms of coastal erosion.

TOM BEARDEN: Jackie Grebmeier, the project’s overall director and Cooper’s wife, says the Arctic will show the effects of climate change earlier than elsewhere.

JACKIE GREBMEIER: These are really sentinel areas, and particularly up here in the arctic where it’s so shallow, and we’re seeing dramatic changes in ice retreat, that it’s kind of the canary in the coal mine type of syndrome.

TOM BEARDEN: The scientists are a mixed group of Ph.D. principal investigators with decades of experience, working alongside post-doctoral, graduate and undergraduate students. They deploy a variety of instruments to make extremely detailed observations of the oceanic environment. One of the largest is called the CTD, for Current, Temperature and Density.

Lou Codispoti has been studying the Arctic for 40 years.

LOU CODISPOTI: One-six. Two-one-two. I got it.

TOM BEARDEN: He and his associates use the CTD to take measurements from the entire water column from the surface to the sea bed.

LOU CODISPOTI: One of the important things of an experiment like this, in addition to all of the scientists here with their own interests, is that we try and get the data in archives so it’ll be useful to the community for long, long periods of time. I mean, it’s high falutin’ to say, but as long as civilization lasts. And I think one of the things I think we’re doing is establishing a baseline for this year during a period when the arctic seems to be going through some changes.

TOM BEARDEN: And that’s why Evelyn Sherr, one of the ship’s principal investigators, believes their research is vital.

EVELYN SHERR, Oregon State University: The data we’re collecting is one of the most comprehensive data sets of the Arctic Ocean ever. The oceans in general are woefully under-sampled, and by taking a large data set over a couple of years, that smoothes out the sample to sample patchiness and we can get a better grasp of the system that — how the system in general is structured and how it functions.

TOM BEARDEN: The focus of the research involves something called the carbon cycle — the way that carbon in all its forms moves back and forth between the oceans, the land and the atmosphere. In the ocean, plants use dissolved forms of carbon dioxide in the water as part of their growth process, then release oxygen as a byproduct. Animals use that oxygen and exhale carbon dioxide, as well as providing nutrients for plants and completing the cycle.

When the animals die, they sink to the bottom. Some carbon remains in their bodies, and in cold temperatures, the carbon can remain buried with them in the ocean deep. But as the temperature rises, the ice coverage in the arctic melts. Bacterial activity in the water can increase and more of the buried carbon, as well as the carbon naturally occurring in the water, will be released into the atmosphere. And since carbon dioxide is a major heat-trapping greenhouse gas, releasing more of it might accelerate global warming.

Tracking changes to the carbon cycle in the arctic is far from easy. Even in summer when the sun shines 24 hours a day, scientists can face brutally cold temperatures as they deploy and recover their sensors.

JACKIE GREBMEIER: Granted it’s beautiful right now, but we have our days in which it’s, you know, everything is freezing; snow freezing on your eyelashes, that type of thing, and you wonder why do you do this type of research. And I think you have to be dedicated then to go through the thick and thins of that. But it is hard work. It’s 24/7, which means we work 24 hours a day, seven days a week.

TOM BEARDEN: It’s also a constant battle to prevent floating ice from damaging the equipment, not to mention wayward polar bears, who treat fragile instruments like toys. But the scientists aren’t studying large animals like the bears, but rather the smallest. Tiny ocean creatures are the foundation of the food chain, and knowing what happens to them will help determine how creatures at the top of the food web — the bears, walrus, and humans — might be affected by climate change.

Each group on board is studying one of the many pieces of the carbon cycle puzzle, from the bottom of the ocean to the top. Graduate student Rebecca Levy starts at the bottom of the ocean. She sorts through a sample of benthic creatures, animals that live in and on the ocean floor. They were collected with this device called a Van Veen Grab. Levy and principal investigator Susan Schonberg, who jokes about still playing in the mud at her age, also find mussels, brittle starfish, and other odd-looking animals that live on the ocean floor.

SUSAN SCHONBERG: So we’ll take all these little dried animals home now and grind them up and run them through a mass spectrometer to find out what their carbon and nitrogen look like. And that way we can see how carbon is flowing through the whole food web — who’s eating who really.

TOM BEARDEN: Carin Ashjian is studying zooplankton. These mostly microscopic animals live in the water column, the area between the deep ocean and the surface. Here she is looking at underwater video of particle distribution.

CARIN ASHJIAN, Woods Hole Oceanographic Institution: This has got a lot of particles in this portion of the water column. It’s pretty amazing. When I first came up here to work in 2002, I was stunned by how many particles there were because it looked more like what I would expect to see or had seen in temperate regions.

TOM BEARDEN: I wouldn’t have expected it in cold water.

CARIN ASHJIAN: Well, it’s very productive here. It gets a lot of nutrients and once the ice goes away, you just get this incredible production.

SHARON SMITH: I wonder what that is. It’s a copepod. It’s a big red copepod.

TOM BEARDEN: Sharon Smith, who is studying large-bodied zooplankton a little closer to the surface, says changes can be harmful to the animals that depend on them for food.

SHARON SMITH: If there’s warming and the currents change such that these organisms are no longer moved onto the shelf each spring, then the baleen whales that come here and the birds that come here would no longer be able to survive. And in turn, they support the subsistence of local populations.

TOM BEARDEN: Although the data is preliminary, the Healy’s scientists report some significant observations from the current voyage. They say much of the sea ice has moved northward to deeper, colder waters. The ice retreat may be taking walruses with it, and because they’re being pulled into these deeper waters further away from their shallow-water food supply, there has been an increase in sightings of walrus pups without their mothers. Without an adult nearby, the situation could be dangerous for the youngsters.

The data also showed that one region being studied reached 41 degrees Fahrenheit, that’s 7 degrees warmer than just two years ago. The Healy scientists say they believe they’re seeing change in the Arctic, but say much more analysis and further research is required to reach solid scientific conclusions. Lee Cooper says that final analysis is the most challenging step.

LEE COOPER: We’ll be working on this for several more years in terms of working up the research results and having the scientific community test us as we submit papers to say, “No, that’s all a crock.” Or maybe they agree or maybe that’s a little bit wrong and you ought to say it this way, and that’s the way science works.

TOM BEARDEN: The first results are expected to be published as early as next year.